package network;

import java.io.IOException;
import java.net.*;
import java.util.Scanner;

public class UdpEchoClient { //回显客户端
     DatagramSocket socket = null;
    private String serverIp;
    private int serverPort;
    //此处ip使用的是字符串(点分十进制)
    public UdpEchoClient(String serverIp,int serverPort) throws SocketException { //请求ip与目的端口
        this.serverIp = serverIp;
        this.serverPort = serverPort;
        socket = new DatagramSocket();//此处(客户端)不需要手动指定端口号 由系统自动分配空闲端口
    }
    public void start() throws IOException {
        System.out.println("客户端启动");
        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.print("->");//提示用户接下来需要输入内容
            //1.从控制台读取要发送的请求数据
            if (!scanner.hasNext()) {
                break;
            }
            String request = scanner.next();
            //2.构造请求并发送
            DatagramPacket requestPacket = new DatagramPacket(request.getBytes(),request.getBytes().length,
                    InetAddress.getByName(serverIp),serverPort);
            socket.send(requestPacket);
            //3.读取服务器的响应
            DatagramPacket responsePacket = new DatagramPacket(new byte[4096],4096);
            socket.receive(responsePacket);
            //4.将响应显示到控制台上
            String response = new String(responsePacket.getData(),0,responsePacket.getLength());
            System.out.println(response);
        }
    }

    public static void main(String[] args) throws IOException {
        UdpEchoClient client = new UdpEchoClient("127.0.0.1",9090);
        client.start();
    }
}